


Running Hot

by majesticduxk



Category: Supernatural
Genre: Ass Play, Demon!Dean, Implied Bottom Dean, M/M, Restraint, attempted humour, dub con, implied future wincest
Language: English
Status: Completed
Published: 2014-06-20
Updated: 2014-06-20
Packaged: 2018-02-05 11:22:50
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,817
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/1816798
Author URL: https://archiveofourown.org/users/majesticduxk/pseuds/majesticduxk
Summary: <blockquote class="userstuff">
              <p>this was written for a kinkmeme fill</p><p> </p><p>  <i>Dean is trying to hide it, whenever his demonic side surfaces. But Sam found out that demons run hotter than humans. So he takes an anal thermometer and takes Dean temperature, whenever he thinks Dean is lying to him. </i></p>
            </blockquote>





	Running Hot

**Author's Note:**

> I kind missed the point. It asked for Sam/Dean (which was in the title line, so how I missed it I don't know) but Cas snuck his way in (which I thought made sense).

Sam sent Dean a disbelieving look. 

“I thought you said you’d checked this out, Dean! You said there were only three vampires?!”

Dean didn’t even have the grace (ha!) to look embarrassed. He just shrugged his shoulders sending innocent green eyes in his direction. “I must have got it wrong, Sammy. Three, nineteen. There’s not much difference when you win in the end.”

Sam pinched the bridge of his nose. In some ways there was nothing different about hunting with Dean. In other ways though… 

Dean was pretty good at hiding his demonic side. But they had an _agreement_. If Dean was feeling even the slightest bit black eyed, he told Sam, and Sam took control – of everything. Of the hunt, in the bunker, even the goddamn laundry if it came down to it. Demonic Dean was too blood thirsty, and nothing was safe. Sam didn’t have enough shirts to lose one every time Dean went black. And up until this point, it had been an honour system: Dean would tell Sam the truth.

Dean had gained and lost many things when he turned into a demon. Unfortunately, one of those things were his tells when he was lying. Until Dean completely demoned out, until Dean’s eyes turned black, Sam had no idea… 

Hence the honour system. 

Which Dean had just broken. 

Again.

Dean idly licked the vampire blood off the knife. Sam closed his eyes. There had to be a better way

\--

“Hello Sam.”

Sam barely jumped. Dean was now silent unless he thought about it, so he was used to supernatural beings appearing behind him. 

“Oh – hey Cas.”

Castiel surveyed the heavy tomes in front of Sam.

“Are you researching for a hunt?”

Sam glanced up again. Now that Dean was kind of out of action, Cas spent a lot more time with Sam. Finding out about Dean of course. But it was still rather uncomfortable being at the end of that stare.

“Ah. No. No.” Sam sat back, stretching. “Trying to find a way to manage Dean. Dean agreed to tell me before he demoned out – it leads to problems on hunts. And on other occasions too…” Despite his best intentions, Sam’s mind drifted back to the convenience store last week. He shuddered. He wanted to avoid something like that happening again at all costs. “Dean agreed that he would tell me, but he’s been lying.”

“He is a demon, Sam.”

Sam glared at Castiel. “I _know_ that, but he is still my brother. And I thought he was your friend!”

Okay. Side tracked. But Sam was feeling cranky, so someone else should feel annoyed too. 

But this was Castiel. Single minded Angel of the Lord. 

“So you are researching…?

Sam gave up. “Demon tells. I figured there was a way of checking if he was lying then I could eventually train him out of it.” 

Castiel looked thoughtful for a moment, then disappeared. 

“Thanks. Bye – Cas!!”

The angel reappeared, a thick book in hand. 

“I believe you will find what you want here, Sam.”

\--

Castiel had been right. The book was exactly what Sam needed. It was amazing.

Although, he wondered why _How to manage your pet demon_ had been on the shelves in Heaven’s Library. He’d gone to ask Cas, but as soon as the angel realized the nature of Sam’s question, he disappeared. Obviously Sam needed the associated angel training manual too. 

While the book was fascinating, there was one section that stood out.

_Whilst a demon doth lie, cheat and steale, of one bodily function they have little control. The internal workings of the fiend are independent to the demon’s mind. Thus a measurement of internal temperature will allow the demon owner to establish Truth from the demon. Even when the being wishes it unknown._

Okay… That was… kind of clear. 

“Cas?”

“Hello, Sam.”

“I read the whole book.”

Castiel nodded. “I would expect nothing less from you.”

“And I’m pretty sure I understand but… how do you take the temperature of a demon? Stick a thermometer in their mouth?”

Castiel looked confused. “Sam. I am an Angel of the Lord. I do not require a thermometer.” Cas did the endearing head tilt again. “Also, thermometers were not invented when the book was written.”

That made sense. But Sam wasn’t a magically able to read demon internal temperatures. And before that he needed to establish a baseline…

“I’m not going to be able to call you every time, but could you do me a favour and establish a baseline? So that I know what his normal temperature is?”

Castiel considered. And Sam snapped. 

“Cas! I don’t know why you’re avoiding him like this!”

“Dean told me he didn’t want to spend time with an angel, so I have been honouring that request.”

Sam sent him a hard look. “Was this right after he changed? When he was drooling, and jabbering, and threatening to send you to hell?”

“Actually, he threatened to smite me.”

Sam’s eyes rolled so hard they hurt. “So you think that a demon threatening to _smite_ an angel might not be totally in his right mind…?”

Castiel had no time to respond as Dean entered the room. 

“Sammy – have you seen – Cas?!”

Dean’s eyes stayed green, so Castiel stepped up, laying a hand on Dean. “Hello, Dean. It is good to see you again.” He turned to Sam. “One hundred and ten.”

He turned back to Dean. “I am sure we will be seeing more of each other.” And then Cas gave that tiny smirk he had, when he thought he was about to say something hilarious. “Stay cool.”

Dean blinked as the angel disappeared. “What was that about it?”

Sam ignored him, instead focusing his research on the best way to take someone’s temperature. 

\--

Sam could admit he’d set Dean up. 

Well, really Dean set himself up. If he told the fucking truth, none of this would have happened. Dean wouldn’t be ass up, pants down over his lap, with an angel holding him in place. 

Cas was surprisingly happy to restrain Dean. 

“Sammy? What the fuck! Let me up. Now!”

Sam tutted. “I don’t even have to look you in the face to know you’ve gone all black eyed, Dean. Just like I know that you lied to me when you said there were only two werewolves.”

“No, Sammy! I just got it…”

Sam interrupted. “I did my research properly this time Dean. Unfortunately you’ve proven I can’t trust you. So Castiel has been helping me to find ways to check if you’r lying. We’re just checking one of them now.”

Dean’s body tensed as he stopped wiggling. “Getting my naked ass over your lap is a way of checking? Dude, I know you’ve wanted me forever. Honestly, you just needed to ask.”

Sam blushed, but ignored the slightly inquiring tilt of Castiel’s brow. Dean was right, but it wasn’t the point. 

“This isn’t going to hurt, Dean…”

Sam slipped a lubed finger between Dean’s asscheeks, rubbing over his tight hole. “At least it shouldn't. You need to relax, Dean. I really don’t want to hurt you.”

Dean responded by clenching his glutes. Sam didn’t mind. A chance to play with his brothers asshole wasn’t to be sneezed at. Castiel’s brow moved into a more knowing position. Goddamn angels and their mind reading abilities. 

Sam pointedly ignored the angel, who shouldn't have been in his fucking mind anyway, focusing instead on teasing at the tight pucker. He knew he could just shove his finger up there – Dean was a demon, he’d suffer no lasting damage – but he really wanted Dean to _enjoy_ this as well. Dean’s smartass comments lead him to believe that Dean had thought about Sam’s cock as much as Sam had thought about burying himself in Dean’s ass. Sam would think about that later. Right now he was playing with Dean’s ass for their own good. 

“Like to look, d’you Cas? Should have known you’d be like that.”

Castiel ignored Dean. “Sam, you should take the measurement now. The heat spike lasts only 45 minutes, and 42 minutes have passed since Dean…”

“Okay Cas! Thanks!”

Sam quickly interrupted. He had this all planned out. 

“The thing is, Dean. Cas let me in on a little secret. Demons lie. We all know that. But there is one way of telling when they lie.” Ah! There it was, finally Sam’s finger breached the tight ring of muscles. Sam smirked, knowing he would have many more opportunities to loosen it up…

“Sam…”

“I know Cas!”

Sam quickly lubed the tip of the thermometer, before removing his finger and seamlessly sliding it home. The thermometer was so small Dean probably hadn’t needed loosening up. But Sam had enjoyed it. 

“Son of a fucking bitch!!! That’s cold, you asshole!”

Sam held it firmly in place. “Get used to it Dean. As I was saying, Cas gave me a wonderful book, all about understanding demons. The most interesting part was about demon tells. Did you know that a demon’s body temperature goes up after they lie?”

Sam watched the thermometer wiggle around as Dean clenched his ass. 

“That’s right, Dean. Luckily, Cas helped me get a baseline. How long is that, Cas.”

“Seventy two point five seconds.”

“And how long does it need to stay in?”

“Ninety seconds.”

Sam patted Dean’s ass. “Better get used to this Dean. You are not going to lie to me anymore, and if I think you are? You’ll be straight back over my lap.”

 

“Ninety seconds, Sam.”

Sam slid the thermometer free. “Oh Dean. One hundred and thirty. You’ve been a bad boy, haven’t you.”

Dean growled. “Whatever, Sammy. Cas won’t always be around to help you!”

Sam smiled, before saying brightly, “I know! That’s why we made you cuffs!”

Castiel slipped them on to Dean’s wrists, before he even realised. “Cas!”

Castiel turned away from Dean’s accusing glance. He didn’t understand why Dean’s ability to make him feel guilty had increased as his demonhood increased. Nodding to himself, Castiel decided it required further research. 

Sam let Dean up, who immediately tried to take the cuffs off. “They’re special cuffs, Dean. They’ll let me restrain you if I need to check if you’re lying.” Sam offered a smile. “Of course, they only work if I really think you’ve lied to me…”

Dean snarled angrily, before storming out of the room. 

“I don’t think he liked that too much,” Castiel offered. “He seemed to find discomfort when you inserted the thermometer.”

“He found it too cold,” Sam responded, mind still with Dean. “I guess I need to find something warmer.”

Sam cocked his head. Something warmer… 

“Cas- Is there any way of altering a human body part to be able to take a demons temperature?”

“Sam…”

Sam gave Castiel his best innocent expression. “It’s for Dean! I don’t want him to be uncomfortable!”


End file.
